Volvo no heat

Discussion in 'Questions From New Drivers' started by Jacobsons2388, Jan 16, 2025.

  1. Jacobsons2388

    Jacobsons2388 Bobtail Member

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    Jan 16, 2025
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    Hi, I have a 2012 Volvo vnl 670 D13. Recently I’ve noticed when I bobtail my coolant gauge stays at zero and I have no heat in the truck if I have a load on me the heat will come back on and the coolant gauge will get up to 170. During the summer everything works fine.Oil pressure is fine. I had Diagnostic work done on it and no fault codes came up and the thermostat was fine. The tech did say it might be my heat/cool cluster since he noticed coffee in between the cracks. Also when I turn the knob to blow face and feet I can barley feel the fan. I live in Illinois so winters aren’t crazy but heat is definitely needed.
     
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  3. AModelCat

    AModelCat Road Train Member

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    Sure sounds like a stuck open thermostat to me.

    Easy check is let it run and as it warms up feel the upper rad hose as far away from the engine as you can. If it gradually warms up with the engine that's usually a good indicator the thermostat is stuck open. Generally the hose will stay cold/cool until the engine hits the cracking temperature of the thermostat and it'll rapidly heat up. Just be mindful of belts, fan, hot exhaust etc when you're doing this.
     
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  4. buzzarddriver

    buzzarddriver Road Train Member

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    Looks to some type of short in the wiring loom. You say it works when you are loaded which pushes down on the rear of the tractor and when bobtail the rear frame is higher due to less weight. Somewhere along the underside of the cab the wires get pinched when frame is getting higher without a load. Just my spitball reasoning.
     
  5. TripleSix

    TripleSix God of Roads

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    If you have a sleeper, the sleeper will have its own blower. Does the blower in the sleeper work?

    Also, some trucks (might be an older model truck thing) have shut off valves to prevent hot coolant from the engine.
     
  6. 77fib77

    77fib77 Road Train Member

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    I'm going with ThermoStat. Open thermostat empty down the road, your running a 100hp. But open it's designed to let 400 hp of heat production to flow threw the hose and radiator. While not overheating.
     
  7. Jacobsons2388

    Jacobsons2388 Bobtail Member

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    Jan 16, 2025
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    I’m going to try what the comments recommended. I haven’t tried the truck heat in the bunk. Because I have a bunk heater maybe.
     
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